AO4701 Equivalent & Substitute Parts

Part Overview

The AO4701 is a P-Channel MOSFET manufactured by Alpha & Omega Semiconductor Inc., rated for 30V drain-to-source voltage and 5A continuous drain current in a surface mount 8-SOIC package. This device features an integrated Schottky diode and is designed for applications requiring P-channel switching and load control in compact form factors.

The AO4701 is classified as obsolete. Identifying equivalent and substitute parts is necessary to maintain design continuity, ensure supply chain availability, and support ongoing production requirements for systems utilizing this component.

Key Parameters

Parameter	Value	Unit
FET Type	P-Channel	—
Drain to Source Voltage (Vdss)	30	V
Continuous Drain Current (Id) @ 25°C	5	A
Rds On (Max) @ 5A, 10V	49	mOhm
Vgs(th) (Max) @ 250µA	1.3	V
Gate Charge (Qg) (Max) @ 4.5V	9.5	nC
Vgs (Max)	±12	V
Input Capacitance (Ciss) @ 15V	952	pF
Power Dissipation (Max)	2	W
Operating Temperature Range	-55 to 150	°C
Package Type	8-SOIC	—
Mounting Type	Surface Mount	—
Moisture Sensitivity Level (MSL)	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution of the AO4701 is determined by strict equivalence across the following critical parameters:

Mandatory Matching Parameters:

FET Type: P-Channel
Drain to Source Voltage (Vdss): 30V minimum
Package Type: 8-SOIC surface mount
Mounting Type: Surface mount
Operating Temperature Range: -55°C to 150°C minimum

Performance Parameters for Functional Equivalence:

Continuous Drain Current (Id): 5A or greater at 25°C
Rds On (Max): 49 mOhm or lower at rated conditions
Vgs(th) (Max): Threshold voltage compatibility within gate drive specifications
Gate Charge (Qg): Lower values indicate faster switching performance
Input Capacitance (Ciss): Lower values reduce gate drive requirements

The SI4485DY-T1-GE3 meets all mandatory matching parameters and exceeds performance specifications in drain current (6A), on-resistance (42 mOhm), and power dissipation capability, making it a direct functional substitute for the obsolete AO4701.

Parameter Comparison

Parameter	AO4701	SI4485DY-T1-GE3	Unit
Manufacturer	Alpha & Omega Semiconductor Inc.	Vishay Siliconix	—
Product Status	Obsolete	Active	—
FET Type	P-Channel	P-Channel	—
Drain to Source Voltage (Vdss)	30	30	V
Continuous Drain Current (Id) @ 25°C	5 (Ta)	6 (Tc)	A
Rds On (Max) @ 10V	49 @ 5A	42 @ 5.9A	mOhm
Vgs(th) (Max) @ 250µA	1.3	2.5	V
Gate Charge (Qg) (Max)	9.5 @ 4.5V	21 @ 10V	nC
Vgs (Max)	±12	±20	V
Input Capacitance (Ciss) @ 15V	952	590	pF
Power Dissipation (Max)	2 (Ta)	2.4 (Ta), 5 (Tc)	W
Operating Temperature Range	-55 to 150	-55 to 150	°C
Package Type	8-SOIC	8-SOIC	—
Mounting Type	Surface Mount	Surface Mount	—
Moisture Sensitivity Level (MSL)	1 (Unlimited)	1 (Unlimited)	—

Engineering Selection Recommendations

Primary Substitute: SI4485DY-T1-GE3

The SI4485DY-T1-GE3 is the recommended substitute for the obsolete AO4701. This selection is based on the following engineering criteria:

Product Status Alignment: The SI4485DY-T1-GE3 maintains active product status with Vishay Siliconix, ensuring long-term availability and continued manufacturing support. This addresses the obsolescence of the AO4701 and provides supply chain stability.

Electrical Compatibility: Both devices share identical drain-to-source voltage ratings (30V) and package configuration (8-SOIC surface mount). The SI4485DY-T1-GE3 exceeds the AO4701 in continuous drain current (6A versus 5A) and delivers superior on-resistance performance (42 mOhm versus 49 mOhm at 10V), enabling equivalent or improved thermal performance in existing circuit designs.

Compliance and Certifications: The SI4485DY-T1-GE3 is RoHS3 compliant and carries identical ECCN (EAR99) and HTSUS (8541.29.0095) classifications as the AO4701. Both devices maintain MSL 1 (Unlimited) moisture sensitivity ratings, supporting standard handling and storage protocols.

Thermal and Operating Characteristics: Both devices operate across the identical temperature range (-55°C to 150°C junction temperature). The SI4485DY-T1-GE3 provides enhanced power dissipation capability (5W at Tc) compared to the AO4701 (2W at Ta), offering additional thermal margin in power-constrained applications.

Gate Drive Considerations: The SI4485DY-T1-GE3 exhibits a higher threshold voltage (2.5V versus 1.3V) and increased gate charge (21 nC versus 9.5 nC), requiring verification that existing gate drive circuits deliver sufficient voltage and current to achieve full on-state performance. Input capacitance is lower (590 pF versus 952 pF), reducing gate drive power requirements.

Frequently Asked Questions (FAQ)

Q: Can the SI4485DY-T1-GE3 directly replace the AO4701 without circuit modifications?

A: The SI4485DY-T1-GE3 is electrically compatible with the AO4701 in terms of voltage rating, current capability, and package footprint. However, gate drive circuit verification is required. The SI4485DY-T1-GE3 has a higher threshold voltage (2.5V versus 1.3V) and increased gate charge (21 nC versus 9.5 nC). Confirm that your gate driver provides sufficient voltage and current to fully enhance the SI4485DY-T1-GE3 at your operating frequency.

Q: What is the significance of the different current ratings (5A for AO4701 versus 6A for SI4485DY-T1-GE3)?

A: The AO4701 is rated for 5A continuous drain current at 25°C ambient temperature (Ta). The SI4485DY-T1-GE3 is rated for 6A continuous drain current at 25°C case temperature (Tc). The SI4485DY-T1-GE3 provides higher current capacity, making it suitable for applications requiring the full 5A of the AO4701 with additional headroom.

Q: Are there package compatibility concerns between these two devices?

A: Both the AO4701 and SI4485DY-T1-GE3 use the 8-SOIC (0.154", 3.90mm width) surface mount package. Pin configurations and footprints are identical, enabling direct PCB-level substitution without layout modifications.

Q: How do the on-resistance specifications compare?

A: The AO4701 specifies 49 mOhm maximum on-resistance at 5A and 10V gate-source voltage. The SI4485DY-T1-GE3 specifies 42 mOhm maximum on-resistance at 5.9A and 10V gate-source voltage. The SI4485DY-T1-GE3 delivers lower on-resistance, reducing conduction losses and heat generation in equivalent current applications.

Q: What compliance certifications apply to both devices?

A: Both the AO4701 and SI4485DY-T1-GE3 carry ECCN EAR99 classification and HTSUS code 8541.29.0095. The SI4485DY-T1-GE3 is RoHS3 compliant. Both devices maintain MSL 1 (Unlimited) moisture sensitivity levels, supporting standard surface mount assembly processes.

Q: Is the AO4701 still available for new designs?

A: The AO4701 is classified as obsolete and is not recommended for new designs. The SI4485DY-T1-GE3 is an active product with confirmed long-term availability and is the appropriate selection for new applications and design refreshes.

Q: How do gate charge differences affect circuit performance?

A: The AO4701 has a gate charge of 9.5 nC at 4.5V, while the SI4485DY-T1-GE3 has 21 nC at 10V. Higher gate charge requires more energy from the gate driver to switch the device. Verify that your gate driver can supply the required charge at your switching frequency without exceeding current or power limits.

Q: What is the impact of input capacitance differences?

A: The AO4701 has input capacitance (Ciss) of 952 pF at 15V, while the SI4485DY-T1-GE3 has 590 pF at 15V. Lower input capacitance in the SI4485DY-T1-GE3 reduces gate drive power dissipation and enables faster switching transitions, benefiting high-frequency applications.

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